strange out memory error

Question

User1596203943 posted
I have a script which allows the user to upload an image file, alongside the original image I wish to create a thumbnail version of the original image where neither the width nor height would exceed 50 pixels and the ratio is maintained.  I run this if statement to determine the new size I require.

if (intOldWidth >= intOldHeight)

{

iW50 = 50;
iH50 = Convert.ToInt32((50 / intOldWidth) * intOldHeight);

}

else

 

{

iW350 = Convert.ToInt32((50 / intOldHeight) * intOldWidth);
iH50 = 50;

}

I then call this command to create the thumbnail image:

System.Drawing.Image img50 = imgInput.GetThumbnailImage(iW50, iH50, null, IntPtr.Zero);

My problem is that if i use my if statement to calculate the relative sizes i get the out of memory error - however if i hardcode the values in it works fine.  Can anyone offer any guidance on this?

Thanks.

Answer 1

User187056398 posted

In integer math, 1 / 2 is zero.

Try using 50.0 to force floating point math.

Answer 2

User1596203943 posted
I'm sorry, i don' think I kow exactly what you are suggesting.

I tried doing the ratio calculation as a float and then converting this to an int when setting the size - but i still got the same Out of memory error displayed.

Answer 3

User187056398 posted

What are the values being passed to GetThumbNailImage?

 

    protected void Button1_Click(object sender, EventArgs e)
    {
        int intOldHeight = 500;
        int intOldWidth = 500;

        // Test1 will equal zero 
        int Test1 = Convert.ToInt32((50 / intOldHeight) * intOldWidth);

        // Test2 will equal 50
        int Test2 = Convert.ToInt32((50.0 / intOldHeight) * intOldWidth);

        // another way
        int Test3 = (int)((50.0 / intOldHeight) * intOldWidth);
    }

 

Answer 4

User1596203943 posted

excellent, i used the (int)((50.0 / intOldHeight) * intOldWidth); approach and it works perfectly.

 Many thanks.